Generally, a heating system, having been applied to residential buildings, such as houses, villas, and apartments, employs a structure involving a wet heating process, in which a pipe is laid under a flooring material of a room in a building and supplied with heating fluid, such as heating water, thereby heating the room of the building. FIG. 13 is a cross sectional view of a so-called wet type ondol heating system of a conventional technique (“ondol” is a Korean traditional floor-embedded heating system).
As shown in FIG. 13, the wet type ondol heating system 1′ according to the conventional technique comprises a heat insulating layer 18′ formed on a slab 26, a porous concrete layer 16 formed on the heat insulating layer 18′, a pipe 13 in a predetermined shape formed on the porous concrete layer 16, and a mortar layer 14 formed on the porous concrete layer 16 such that the pipe 13 is completely covered with the mortar layer. 14, on which a finishing material 22 is provided, completing a floor structure of the room of the building.
Here, the wet type ondol heating system 1′ shown in FIG. 13 has a structure wherein the porous concrete layer 16 is formed with an air layer therein, so that the air layer absorbs noise or vibration transmitted to the slab layer 26 and prevents heat in the pipe 13 from being transmitted in a direction of the slab layer 26 when the pipe 13 is supplied with heating water, leading to reduction in thermal loss, and wherein the heat insulating layer formed under the porous concrete layer 16 also prevents thermal loss from the pipe 13.
In the above structure of the heating system, it is desirable that the porous concrete layer 16 has a sufficient thickness. Accordingly, in most cases, the heat insulating layer 18′ has a thickness of 20 mm, the porous concrete layer 16 has a thickness of 70 mm, and the mortar layer 14 has a thickness of 30 to 40 mm. As a result, the conventional ondol heating system has a total thickness of approximately 120 to 130 mm from the slab layer 26 to the finishing material 22.
Accordingly, the conventional ondol heating system has problems due to the structure thereof as follows.
First, due to poor heat insulating effect of the porous concrete layer 16 and the heat insulating layer 18′, the conventional heating system has a low thermal efficiency. For instance, in the structure of the heating system shown in FIG. 13, the heating water having a temperature of about 70˜80° C. must be supplied from a heating water supplier to the heating system in order to heat the floor surface of the room to a temperature of about 30° C., leading to a large thermal loss. Therefore, the conventional heating system is disadvantageous in view of energy consumption.
Second, since the noise and vibration cannot be effectively prevented from being transmitted to an upper portion only with the porous concrete layer 16, the conventional heating system is weak in sound absorbing function, and thus, it cannot satisfy sound absorbing requirements for residential constructions, particularly, such as apartments.
Third, since the porous concrete layer 16 and the mortar layer 14 are formed on the entire floor surface, construction time is extended by a time required for curing cement. Furthermore, when there occurs a problem in the pipe 13, such as a water leakage, the mortar layer 14 must be broken in order to repair the pipe 13, thereby making it difficult to repair the heating system, and requiring a large expenditure for repairs.
In order to solve the problems of the conventional heating system as described above, a dry type heating panel made of concrete, synthetic resin, or yellow clay, which is embedded with a pipe for carrying heating water therein, or which is provided with grooves or fixing members for installing the pipe for carrying heating water, was developed. The dry type heating panel is an assembly type heating panel, and has advantageous effects in that the construction of the heating system may be completed by simply assembling previously produced dry type panels, thereby reducing the construction time, and simplifying maintenance and repair operations thereof. However, the dry type heating panel has problems in that since it adopts a line heating structure in which radiation heat is mainly concentrated where the pipe for carrying heating water is located, generating a severe temperature variation in the heating system, the dry type heating panel is ineffective in view of heating efficiency, and in that since the pipe itself is made of metal or synthetic resin, it is expensive, resulting in increased construction costs. Furthermore, thermal loss may occur due to piping, and dewing phenomenon may occur on the surface of the pipe, thereby wetting the panel.
In order to solve the problems of the conventional dry type heating panel described above, as disclosed in U.S. Pat. No. 5,080,166 and Korean Patent Laid-open publication No. 2002-95733, a plate type heating panel provided with an inner fluid pathway for allowing the heating water to flow therethrough was developed. Compared with the dry type heating system adopting the line heating structure, the plate type heating panel having the inner fluid pathway therein adopts a plane heating structure in which the heating water flows not in a local area but in an overall area, so that it has very high heating efficiency, resulting in reduction of fuel expenses, and so that the pipe is not required for the structure of the plate type heating panel, thereby eliminating a complicated piping work and reducing the expenses for piping. Additionally, the plate type heating panel is not subject to the thermal loss and the dewing phenomenon, which usually occurs on the surface of the pipe in the structure of the dry type heating panel, and allows a weight of the panel to be reduced. Furthermore, the plate type heating panel is very easy to construct and repair.
However, as shown in FIG. 2, a conventional plate type heating panel 2′ having the inner fluid pathway has a disadvantage in that since the inner fluid pathway 12′ has a hexagonal shape, it is structurally very weak at an angled portion of the hexagonal shape. Furthermore, compared with an individual heating system in which the heating fluid has a water pressure of 3.5 kgf/cm2 or less as a maximum value, in case of a central heating or a district(regional) heating, the heating fluid has a water pressure of about 6 to 7 kgf/cm2 as a maximum value, and may have a local water pressure over 6 to 7 kgf/cm2 due to a site or height of the building. Accordingly, when installing the inner fluid pathway-embedded heating panel in the central heating or in the district heating, a pressure resistance of the heating panel must be considered in order to prevent a deformation or leakage of the panel, which may be caused by the water pressure condition as mentioned above.
Japanese Utility Model Laid-open Publication No. (Sho)51-69458 discloses a bottom heating type panel using heating water, which comprises a heat insulating bottom panel with zigzag-shaped grooves formed thereon, a pipe for carrying heating water fixed to the zigzag-shaped grooves, and a metal plate for heat radiation formed on the heat insulating bottom panel while contacting the pipe for carrying heating water. However, since the bottom heating type panel employs the line heating structure, it has a low thermal efficiency, and regardless of double floors in a floating structure, it has a low sound absorbing performance due to absence of sound absorbing/vibration isolating layers.
Korean Patent Laid-open Publication No. 1995-6363 discloses an assembly type ondol plate having an inner heating water pathway. However, the inner heating water pathway of the ondol plate also has a hexagonal shape, and thus it is structurally very weak at an angled portion of the hexagonal shaped inner heating water pathway.